The cation M2+ reacts with NH3 to form a series of complex ions as follows:

Question

M2+ + NH3 M(NH3)2+ K1 = 102
M(NH3)2+ + NH3 M(NH3)2
2+ K2 = 103
M(NH3)2
2+ + NH3 M(NH3)3
2+ K3 = 102
A 1.0 × 10–3 mol sample of M(NO3)2 is added to 1.0 L of 15.0 M NH3 (Kb = 1.8 × 10–5). What is the dominant species in this
solution? EXPLAIN. (don’t have to calculate here)
a) M2+
b) M(NH3)2+
c) M(NH3)2
2+
d) M(NH3)3
2+
e) M(NO3)2

Answer 1

the answer is D - not sure why though but that is the answer according to another site.